Samuel Armstrong, 24, was accused of attacking the young parliamentary worker when she fell asleep after a night drinking in the Houses of Parliament.

A Conservative MP’s chief of staff has claimed he was cleared of raping a woman in his boss’s office after “crucial evidence” was disclosed just days before his trial.

The complainant, who is in her twenties, said she “felt like a hostage” and claimed she was raped twice by South Thanet MP Craig Mackinlay’s senior aide.

MP Craig Mackinlay is calling for debate on anonymity for those accused of rape (Victoria Jones/PA)

But Armstrong, who was arrested after the woman was captured on CCTV running through the corridors of Westminster in tears in the early hours of October 14 last year, insisted they had consensual sex.

On Thursday, he wiped tears from his eyes after a jury of seven women and five men found him not guilty of two counts of rape, one of sexual assault and one of assault by penetration, after a two-week trial at Southwark Crown Court.

Jurors took more than five hours to return verdicts and Armstrong was comforted by his father Andrew as he left the dock before speaking to the media outside court.

“My whole life has been turned upside down. For a year I have not slept or eaten, and I was innocent,” he said.

“Were it not for the fact that crucial evidence was disclosed to my defence team just eight working days before trial, there could well have been yet another miscarriage of justice in this case.”

Mr Armstrong and his lawyers refused to elaborate on what evidence he was referring to, but the court heard the complainant initially refused to give police access to her mobile phone and medical records.

In messages recovered from her phone, she said she had contacted a journalist just hours after the alleged attack to secure a “sympathetic” write-up, while her medical notes revealed details of a history of mental health issues, including depression and anxiety.

Armstrong, from Danbury in Essex, has been suspended from his job since the allegations arose.

Following the verdicts, Mr Mackinlay said on Twitter: “I am very pleased for Sam, a young man whose life has been destroyed over the past 14 months.

“Debate now needed over anonymity of those accused, especially in a week where actions of the authorities in such cases have been found wanting.”